1. Field of the Invention
The present invention relates to a manifold block for an internal combustion engine and in particular a manifold block that promotes mixing of fuel and air in the engine upstream of the cylinder head, improving the efficiency, emissions profile and/or power of the engine. The block may also incorporate an induction regulator further to facilitate fuel/air mixing.
2. Description of the Related Art
It is well known to use a fuel injector to control the fuel/air mixture ratio in an engine. Conventional fuel injection systems are generally adapted to monitor the amount of fuel supplied to the engine, or to each cylinder thereof, the timing and duration of each injection event being controlled to provide a desirable fuel/air mixture in the cylinder. However, conventional injector systems are generally not designed to optimize the mixing of fuel and air upstream of the cylinder(s), and the present invention seeks to provide a means for optimizing this aspect of injector systems.
WO-A-01/63107 discloses an internal combustion engine for liquid petroleum gas or compressed natural gas and particularly an internal combustion engine fitted with a pressure release valve operable (by electrical or mechanical means) to open during the compression stroke if the pressure in the cylinder exceeds a predetermined value corresponding to the maximum desired compression ratio in the cylinder, but is held shut during the ignition stroke. When the valve is open during the compression stroke, excess fuel/air mixture is bled from the cylinder and passes through a one-way valve and a cryocooler to the inlet manifold where it mixes with fresh incoming air. The system may also be used in petrol/diesel engines which have been modified to use gas as fuel.
GB-A-2,390,116 discloses an intake manifold, fuel rail and moulded injector pack assembly for internal combustion engines having configurations which result in the necessity for only a single seal at the connection between the fuel rail and moulded injector pack assembly.
WO-A-02/25092 discloses a method and apparatus for mechanically gasifying an atomized fuel/air mixture. This apparatus comprises a housing in which is disposed a stator body, the inner surface of which has an array of pins projecting inwards therefrom. There is also provided a rotor body having an array of pins projecting outwards from the outer surface thereof. The rotor is arranged to rotate at high speed and is located such that its pins intermesh with those of the stator. A motor (driven by compressed air/exhaust gas/electrical motor) is provided to drive the rotor. The housing is closed at either end save for an inlet at one end for receiving atomised fuel from an injector, and an outlet at the other end for directing gaseous fuel into an intake manifold/intake valves of an internal combustion engine. The fuel is gasified by way of the rotor/stator pins striking fuel droplets, thereby creating smaller droplets. In one embodiment, the “stator” may be arranged to rotate in a direction opposite to that of the rotor to increase relative velocities between the pins.
U.S. Pat. No. 5,673,673 discloses a method and apparatus for injecting gaseous fuel at velocities of the order of Mach 1 into an air stream flowing into an intake port of an internal combustion engine. The apparatus is mounted between the intake port of the internal combustion engine and the air intake manifold. The injection apparatus is arranged to inject the gaseous fuel into the air stream at between Mach 0.5 and Mach 1 to achieve uniform mixing of the fuel and air. Key to achieving these high injection speeds are the effective flow areas of the injector metering orifice (i.e. the orifice from which the gaseous fuel leaves the injector and enters a conduit leading to a discharge orifice) and the conduit discharge orifice. In particular, an effective flow area for the conduit discharge orifice of between two and five times greater than the effective flow area of the injector metering orifice is effective in achieving these high injection speeds. A further requirement for achieving the high injection speeds is that the pressure at which the gaseous fuel is supplied is more than four times the air intake manifold absolute pressure.
GB-A-2,409,499 discloses a regulator with driven propeller for intake or exhaust manifolds of internal combustion engines.
U.S. Pat. No. 4,478,607 discloses a device for atomizing and dispersing fuel in a fuel/air mixture. The fuel mixer/atomizer comprises a hollow cylindrical body provided with a propeller to mix the air and fuel (driven by fuel flow) and a screen serving the dual purpose of trapping debris and further atomizing the fuel.
U.S. Pat. No. 6,269,805 discloses a manifold spacer, which comprises an apparatus adapted to be inserted between an outlet of a carburettor and the inlet of an intake manifold. The apparatus comprises a body member having an opening therethrough, the size of which is consistent with the outlet opening of the carburetor and the inlet of the intake manifold. Nitrous oxide and fuel manifolds span the opening and are provided with a plurality of orifices to direct spray downwards towards the inlet of the intake manifold.
These prior art devices each suffer from one or more of the following disadvantages: they are overly complex in design, giving rise to additional cost and likelihood of mechanical failure; they are difficult to retrofit; they do not work satisfactorily in practice to improve engine performance; they do not work satisfactorily in practice to decrease engine emissions. It is an object of the present invention to provide an induction regulator block for an internal combustion engine which ameliorates one or more of the aforesaid problems. In particular, it would be desirable to provide a means for retrofitting to an existing engine a device effective to improve the mixing of fuel and air supplied to the cylinder head (or heads) thereof.
It is therefore an object of the present invention to provide a manifold block for an internal combustion engine for improving the efficiency, emissions profile and/or power thereof.